I'll add my anecdotal experience, got covid in 2020, got the vaccine a year later and felt butterflies in my chest immediately after. Went away after a few seconds but after a month discomfort started during intense exercise. Another month later and I went to the ER with mild pericarditis. Its been a long ~year of recovery where I had to keep my HR under 100 and take tons of anti-inflammatories. Got lucky that I had it mild and finally back to normal (minus getting out of fitness), lets hope it stays that way.

What I learned (perhaps too late lol): * Medical Science is largely empirical (requires statistical nous), unfortunately doctors do not understand statistics, take argmaxes and treat things deterministically in the guise of evidence based medicine. * Said doctors advise Insurance companies so any doctors that do understand statistics will be bounded within the confines of what the insurance company considers evidence based medicine. This creates wasted work and even frustration as the doctor has to jump through hoops to get things done. * getting a rare disease or disease with uncertainty requires becoming an expert on it to "correctly" navigate the health system (US here). I have a newfound appreciation for not only those who have to deal with insurance but simply navigating the uncertainty.